We hope to make better progress in obtaining authentic selenocysteic acid and selenotaurine. The synthesis of both compounds is reported in the literature. Once we have these compounds in our hands, we can prove or disprove that selenomethionine is metabolized to selenocysteic acid and selenotaurine specifically, not just to higher oxidation-state compounds. To investigate the biochemical and toxicological responses of mice administered either selenocystine or selenocystamine. To determine the effect of selenium toxicity and selenium deficiency on the efficiency of oxidative phosphorylation in mouse liver mitochondria. To investigate metabolic pathways of selenium in E. coli and compare these pathways to those of sulfur.